The pressure regulator is used to regulate, according to the predetermined pressure, a pressure of compressed air fed from a pneumatic source that is the fluid supply source, and to supply the compressed air to a pneumatic operating appliance such as a pneumatic cylinder. The pressure regulator has, as disclosed in for example Japanese Patent Application laid-Open Publication No. 10-268943, a primary-side port to which compressed air is supplied, and a secondary-side port to which a pneumatic operating appliance is connected, wherein an end portion of an opening of a communication hole that communicates with both ports may be opened and closed by a valve element. A spring force in a direction of closing a valve seat of the end portion of the opening is applied to the valve element by a valve spring. The pressure regulator has a diaphragm that is elastically deformed by a differential pressure between a set pressure of the secondary-side port and an atmospheric pressure. A relief hole, through which air at a secondary level is discharged to an outside, is formed in the diaphragm. A tip of a stem attached to the valve element abuts on the diaphragm to close the relief hole, and a spring force in a direction of opening the valve seat through the stem is applied to the diaphragm by a pressure-regulating spring.
In the pressure regulator as mentioned above, when a pressure of a secondary side is lower than a set pressure, the spring force of the pressure-regulating spring causes the diaphragm to open the valve seat via the stem, and the compressed air on a primary side is supplied to the secondary-side port. When a pressure of the compressed air in the secondary-side port reaches the set pressure, a pneumatic pressure applied to the diaphragm causes the diaphragm to be displaced in a direction of separating from the valve element, and the valve element contacts with and closes the valve seat, whereby a communication with the primary-side port and the secondary-side port is cut off.
Meanwhile, when a secondary-side pressure rises higher than the set pressure, the diaphragm is displaced in the direction of separating from the valve element, and the diaphragm separates from a tip of the stem to open the relief hole, whereby the secondary-side pressure is discharged to the outside. When the secondary-side pressure falls, the diaphragm contacts with the stem to close the relief hole. Accordingly, for example, in reducing a pressure in compressed air supplied to the pneumatic operating appliance when a pressure used for a pneumatic circuit having the pneumatic operating appliance is decreased, a new secondary-side pressure is set low. By doing so, the compressed air in a secondary-side pipe is exhausted via the relief hole to the outside up to the set pressure that has been newly set. Also, when the set pressure on a secondary side rises due to applying from the outside a load in a direction opposite to an operating direction of a rod of the pneumatic cylinder etc., the compressed air in the secondary-side pipe is exhausted via the relief hole to the outside to make the set pressure constant.
When a pressure in the compressed air supplied to the secondary-side port is set to actuate intermittently the pneumatic operating appliance such as a pneumatic cylinder, air on the secondary side is consumed, and its pressure is also changed intermittently, whereby the valve seat is more frequently opened and closed by the valve element. Therefore, since a flow of the compressed air from the primary-side port to the secondary-side port becomes intermittent, the valve element vibrates, whereby vibration noises occur, and the secondary-side pressure varies constantly, as a result of which stability deteriorates. Meanwhile, when the air in the secondary-side pipe is exhausted via the relief hole, the diaphragm vibrates by a reverse flow of the air from the secondary-side port to the relief hole, whereby vibration noises occur, and the secondary pressure varies constantly, as a result of which stability deteriorates. When the valve element and the diaphragm vibrate, abrasion of a seal member provided to the valve element is promoted, and degradation of the diaphragm is promoted, as a result of which durability of the pressure regulator deteriorates. Further, the concurrently occurring vibration noises may make even a work environment degenerate.
Known as a vibration controller that suppresses vibration of a vibration element is a dynamic-vibration absorbing apparatus. The dynamic-vibration absorbing apparatus comprises a mass body, a spring, and a damper, wherein the mass body is attached to a vibration controlled object via the spring. When the vibration controlled object vibrates, the mass body of the dynamic-vibration absorbing apparatus vibrates, and part of vibratory energy that the vibration controlled object has is converted into vibration energy of the mass body, whereby the vibration of the vibration controlled object is suppressed. Japanese Patent Application Laid-Open Publication No. 2007-285320 discloses a dynamic-vibration absorbing apparatus for absorbing vibration of a substrate of an electric appliance, and Japanese Patent No. 3911372 discloses a dynamic-vibration absorbing apparatus for suppressing vibration that occurs from an electric mechanism assembled in a microscope. The dynamic-vibration absorbing apparatuses have been called dynamic vibration absorbers or dynamic vibration reducers.